| hree approaches were employed to examine the control of flagellar motors in Escherichia coli. (1) The E. coli flaA locus, which encodes a key component of the switch controlling flagellar rotation, was sequenced and the site of transcriptional initiation was determined. Two reading frames, flaAI and flaAII, span the locus. flaAII corresponds to the flaA locus defined by previous mutations. flaAI has not been identified previously, but a flaAI deletion, which produced a truncated FlaAI peptide in minicells, identifies the FlaAI protein. (2) At least two chemotaxis gene products, CheY and CheZ, directly control the flagellar motor during bacterial chemotaxis. In the absence of other functioning signal-transducing gene products, CheY overproduction makes free-swimming cells tumble more frequently. The CheY dose-response curve for free-swimming behavior was sigmoidal, with a Hill coefficient of 2.4... |
